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Alexander Fleming

✨ 1881–1955, Bacteriology and medicine

Alexander Fleming (1881–1955) was a Scottish bacteriologist whose work changed the treatment of bacterial infections. Born on 6 August 1881 near Darvel, Scotland, he studied medicine in London and later worked at St Mary’s Hospital. In 1922, he discovered lysozyme, an enzyme found in secretions such as tears and saliva that can damage certain bacteria.

His best-known discovery came in 1928. While studying bacteria, Fleming noticed that a mould had appeared accidentally on a culture plate and stopped nearby bacteria from growing. He identified the active substance and named it penicillin, showing that it could inhibit several disease-causing bacteria.

Fleming published his findings in 1929, but turning penicillin into a reliable medicine required further research. During the 1930s and early 1940s, Howard Florey, Ernst Boris Chain and their colleagues developed methods to purify penicillin and produce it on a larger scale, making treatment of patients possible.

Mass production during the Second World War transformed the treatment of many bacterial infections. Fleming, Florey and Chain shared the 1945 Nobel Prize in Physiology or Medicine for the discovery of penicillin and its curative effect in infectious diseases. Fleming died in London on 11 March 1955. His discovery was crucial, but developing penicillin into a practical medicine was a collective scientific achievement.

💡 Did you know?

The messy laboratory. Alexander Fleming was a brilliant but somewhat messy scientist. Before going on vacation, he left bacterial culture plates lying around. Upon his return, he noticed that a green mold had grown in one plate and that, all around it, the bacteria had died! If he had done the dishes before leaving, he might never have made his discovery!

'Mold juice'. Fleming called his discovery 'mold juice' at first! He understood that this fungus (which resembles that of old cheese) produced a substance capable of beating the fiercest microbes. He renamed it 'Penicillin' after the Latin name of the fungus: Penicillium.

The bacteria artist. In addition to being a doctor, Fleming loved art. He painted small drawings using different colored bacteria in his lab boxes! It's perhaps this habit of closely observing his microbiological cultures that helped him notice the miracle effect of penicillin.